1. Field of the Invention
This invention generally relates to photographic apparatus but more specifically to an optical adapter by which a photographic motion picture camera can be optically coupled to an endoscope to permit a clinician to simultaneously view and photograph, via the camera's optical system, the image formed by the endoscope's eye piece.
2. Description of the Prior Art
Endoscopes are well-known medical optical viewing devices which are useful in the diagnosis of disease. By providing a means for visually examining the interior of body organs for the presense of pathological processes, the endoscope can be used to confirm by direct observation what pathology may be suspected or indicated by other clinical and laboratory findings.
It is useful, and indeed, often desirable for the clinician conducting an endoscopic examination to have a permanent photographic record of his findings. For example, it should be apparent that such records can be used for teaching purposes, as a comparison for evaluating changes in the pathology, or as an aide for promoting communication between the examining clinician and others involved or interested in the diagnosis.
In spite of the obvious benefits which endoscopic photographs have, it should also be apparent that they should not be obtained where the patient's safety may be threatened or his discomfort may be added to by the process by which the photographs are obtained. Therefore, apparatus used for endoscopic photography must be easy to use, must not unduly prolong the endoscopic examination, must be mechanically and optically compatible with the particular endoscope chosen for the examination and must be capable of reliably producing photographs which are acceptably exposed and which contain adequate detail.
Providing photographic apparatus which satisfy these requirements can be difficult given the nature of the problems involved in endoscopic photography. For instance, the particular camera chosen must be able to focus on the image provided by the endoscope's eyepiece, adequate lighting must be provided, the clinician, and sometimes more than one, must be able to see the image immediately before and after the picture is taken in the case of stills and continuously for motion pictures, and all of this usually must be accomplished by apparatus which shares the endoscope's single optical path.
In the past, these problems have been dealt with in a variety of ways by providing either specially designed photographic systems whose use is limited to endoscopic photography or by providing adapters by which existing cameras can be used with an existing endoscope. For examples reference may be had to U.S. Pat. No. 3,368,643 issued to John E. Hotchkiss on Feb. 1, 1972 and entitled "Endoscope for Photographic Recording"; U.S. Pat. No. 3,918,072 issued to Toshihiro Imai et al on Nov. 4, 1975 and entitled "Single-Lens Reflex Optical System For An Endoscope"; U.S. Pat. No. 3,995,287 issued to Karl Storz on Nov. 30, 1976 and entitled "Endoscopic Camera"; and an article by Brian Stanford which appeared in The Journal of Photographic Science, volume 3, January 1955 and entitled "Theoretical First Principles of Endoscopic Photography".
However, none of the foregoing publications appear to deal directly with the specific problem with which the present invention is concerned. In particular, the primary object of the present invention is to provide an adapter by which a motion picture camera having a through-the-lens viewing system with an entrance pupil that occupies only a portion of its taking entrance pupil can be used with an optical viewing device such as an endoscope which has an exit pupil that is smaller in size than the camera's entrance pupil and still satisfy the requirement that the image formed by the viewing device's eyepiece can be viewed continuously while being photographed.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the apparatus possessing the construction, combination of elements, and arrangement of parts which are exemplified in the following detailed disclosure.